Method for enriching burnt-sweet aroma note in yunnan flue-cured tobacco and aerosol-forming material

Abstract

The present disclosure belongs to the technical field of tobacco products, and specifically relates to a method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco and an aerosol-forming material. In the present disclosure, by selecting a C18 column for elution with a specific eluent under a certain pressure, a primary elution step can remove impurities as much as possible, and a secondary elution can elute components of a burnt-sweet aroma note as comprehensively as possible to achieve the enrichment of target components. This method is simple to operate, can realize the efficient enrichment of the components of the burnt-sweet aroma note in the Yunnan flue-cured tobacco extract, and can remove the impurity components therein. When the enriched sample is used in e-cigarette e-liquid, the burnt-sweet aroma of the e-liquid is prominent and the overall tobacco aroma is harmonious.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of tobacco products, and specifically relates to a method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco and an aerosol-forming material.BACKGROUND

[0002] An electronic atomization device is a device capable of vaporizing an aerosol-forming material (including but not limited to atomization liquid, heat-not-burn cigarettes, etc.) into an aerosol for a user to inhale. The electronic atomization device has the advantages of not requiring combustion, causing less harm to the human body and the environment, and being capable of meeting consumers' demand for nicotine to a certain extent. However, compared with traditional cigarettes, the smoke generated by the aerosol-forming material has a relatively large difference from that of real cigarettes in aroma and taste, and its aroma notes are not prominent. These deficiencies greatly affect the quality of the electronic atomization device, and at the same time, also restrict the popularization and popularity of the electronic atomization device.

[0003] When the leaves of Yunnan flue-cured tobacco are mature, their color ranges from golden yellow to orange yellow, mainly orange yellow. The leaves have a saturated color tone, are of moderate thickness, and are rich in greasiness and glossiness. The leaf tissue structure is loose, soft, and has good elasticity. The chemical components contained in the leaves are well-coordinated. The contents of total sugar and reducing sugar are higher than those in other tobacco-growing regions in China, giving it unique characteristics. In the regional division of the flavor style characteristics of flue-cured tobacco leaves across China, Yunnan flue-cured tobacco has the style characteristics of being fresh and ethereal, sweet and elegant, rich and full-bodied, mellow and delicate, mainly with a clear sweet aroma and a roasted sweet aroma as the primary aroma notes.

[0004] Currently, in this field, people are actively exploring the use of different extraction and separation technologies to continuously obtain aroma substances suitable for an aerosol-forming material from various types of tobacco. The main methods include the solvent extraction method, supercritical extraction method, molecular distillation method, rectification method, etc. The expression of the burnt-sweet aroma in the aerosol-forming material is mainly achieved by directly adding monomers, cocoa extracts, Yunnan flue-cured tobacco extracts, etc. for formulation, which may result in problems such as the burnt-sweet aroma not being prominent or the overall tobacco aroma having poor harmony. Although some methods for separating components of a burnt-sweet aroma note from other tobacco leaf varieties have been disclosed in the prior art, they cannot effectively remove the impurity components. In addition, the relevant research and applications regarding Yunnan flue-cured tobacco mainly focus on the clear sweet aroma and the roasted sweet aroma as the research objectives. The aroma components with different aroma notes in tobacco are small in quantity and complex. How to obtain natural burnt-sweet aroma components with a low impurity content from tobacco and apply them to the aerosol-forming material to make the overall tobacco aroma harmonious and produce products with an obvious burnt-sweet style is a major challenge.SUMMARY

[0005] Therefore, the technical problem to be solved by the present disclosure is to overcome the defects in the prior art, such as the absence of a method for enriching a burnt-sweet aroma note from Yunnan flue-cured tobacco, or the methods for enriching from other tobacco leaves exhibiting a relatively high content of impurities, the burnt-sweet aroma of the aerosol-forming material not being prominent, or the overall tobacco aroma having poor harmony. Thus, the present disclosure provides a method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco and an aerosol-forming material.

[0006] Therefore, the present disclosure provides the following technical solutions.

[0007] In a first aspect, the present disclosure provides a method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco, including steps of: S1: diluting a Yunnan flue-cured tobacco extract with a diluent to obtain a diluted solution; S2: subjecting the obtained diluted solution to an elution treatment using a C18 column under a pressure of 5-20 bar, where the elution treatment includes: first performing a primary elution with a first eluent, then performing a secondary elution with a second eluent, and collecting a secondary elution solution, where the first eluent is water or an aqueous ethanol solution with a mass concentration of less than 10%, and the second eluent is an aqueous ethanol solution with a mass concentration of 38-42%; and S3: concentrating the collected secondary elution solution to obtain a sample with the burnt-sweet aroma note.

[0008] In some optional embodiments, in step S2, the flow rate of the elution treatment is 20 mL / min-80 mL / min.

[0009] In some optional embodiments, in step S2, the amount of the first eluent is 3 BV-5 BV; and / or the amount of the second eluent is 3 BV-5 BV.

[0010] In some optional embodiments, in step S1, the mass ratio of the Yunnan flue-cured tobacco extract to a solvent is 1:1-1:5.

[0011] In some optional embodiments, in step S1, the diluent includes at least one of water, ethanol, propylene glycol, and glycerol.

[0012] In some optional embodiments, in step S3, concentration under reduced pressure is adopted; and / or the concentration is performed until the density of a concentrated solution is 1.1920-1.208 g / cm3.

[0013] In some optional embodiments, in step S3, the temperature for the concentration under reduced pressure is 45-65°C, and the pressure for the concentration under reduced pressure is 60-120 mbar.

[0014] In a second aspect, the present disclosure provides a sample of a burnt-sweet aroma note of Yunnan flue-cured tobacco enriched by the above method, including 20-30 µg / mL of furfural, 20-30 µg / mL of 3-methyl-1,2-cyclopentenedione, 20-25 µg / mL of maltol, and 35-40 µg / mL of 2-cyclopentene-1,4-dione.

[0015] In a third aspect, the present disclosure provides an aerosol-forming material, including the above sample of a burnt-sweet aroma note of Yunnan flue-cured tobacco.

[0016] In some optional embodiments, the aerosol-forming material includes 0.5-2 wt% of the sample of the burnt-sweet aroma note of Yunnan flue-cured tobacco and 98-99.5 wt% of a solvent; optionally, the solvent is a mixed solvent of propylene glycol and glycerol; and further optionally, the mass ratio of the propylene glycol to the glycerol is 6:4-1: 1.

[0017] In the present disclosure, the Yunnan flue-cured tobacco extract is an ethanol extract of Yun 87, which can be obtained through commercially available channels.

[0018] In the present disclosure, the C18 column is Daiso RPS C18, 50 um, which can be obtained through commercially available channels.

[0019] The technical solution of the present disclosure has the following advantages: the method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco provided in the present disclosure includes steps of: S1: diluting a Yunnan flue-cured tobacco extract with a diluent to obtain a diluted solution; S2: subjecting the obtained diluted solution to an elution treatment using a C18 column under a pressure of 5-20 bar, where the elution treatment includes: first performing a primary elution with a first eluent, then performing a secondary elution with a second eluent, and collecting a secondary elution solution, where the first eluent is water or an aqueous ethanol solution with a mass concentration of less than 10%, and the second eluent is an aqueous ethanol solution with a mass concentration of 38-42%; and S3: concentrating the collected secondary elution solution to obtain a sample with the burnt-sweet aroma note. In the present disclosure, by selecting the C18 column for elution with a specific eluent under a certain pressure, the primary elution step can remove impurities (including impurities such as polysaccharides and proteins) as much as possible, and the secondary elution can elute components of a burnt-sweet aroma note as comprehensively as possible to achieve the enrichment of target components. If the ethanol concentration in the second eluent is too low, the components of the caramel aroma note cannot be completely eluted, resulting in partial loss. If the ethanol concentration in the second eluent is too high, other impurities will be brought in. This method is simple to operate, can realize the efficient enrichment of the components of the burnt-sweet aroma note in the Yunnan flue-cured tobacco extract, and can remove the impurity components therein. When the enriched sample is used in the aerosol-forming material, the burnt-sweet aroma of the aerosol-forming material is prominent and the overall tobacco aroma is harmonious.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to illustrate the technical solutions in the specific embodiments of the present disclosure or in the prior art more clearly, the following will briefly introduce the drawings required in the description of the specific embodiments or the prior art. It is obvious that the drawings in the following description are some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

[0021] FIG. 1 shows detection results of burnt-sweet aroma components in an ethanol extract of Yun 87 of the present disclosure, sample 1-2 obtained in Example 1, and sample 2-2 obtained in Comparative Example 1.DETAILED DESCRIPTION

[0022] The following examples are provided to better understand the present disclosure. They are not limited to the most preferred embodiments, and do not constitute a limitation to the content and the scope of protection of the present disclosure. Any product identical or similar to the present disclosure obtained by anyone under the inspiration of the present disclosure or by combining the present disclosure with the features of other prior art shall fall within the scope of protection of the present disclosure.

[0023] For those examples in which specific experimental steps or conditions are not specified, the operations or conditions of the conventional experimental steps described in the documents in the art can be carried out. For those reagents or instruments for which the manufacturers are not specified, they are all conventional reagent products that can be obtained through commercially available channels.Example 1

[0024] This example provided a method for enriching a burnt-sweet aroma note in a Yunnan flue-cured tobacco extract, and the specific steps and operating parameters were as follows: (1) sample dilution: the Yunnan flue-cured tobacco extract (ethanol extract of Yun 87) was diluted with propylene glycol as the diluent according to a mass ratio of 1:3 to obtain a diluted solution; (2) medium-pressure preparation: the diluted solution obtained in step (1) was subjected to gradient elution using a medium-pressure preparative C18 column (Daiso RPS C18, 50 um, 2.0 kg of packing material, column size 460 × 100 mm). Water, a 40 wt% aqueous ethanol solution, an 80 wt% aqueous ethanol solution, and a 95 wt% aqueous ethanol solution were separately used as the elution solutions. Under a pressure of 10 bar, gradient elution was performed at a flow rate of 50 mL / min, and the amount of each eluent was 5 BV. The solutions eluted in each gradient were collected; (3) filtration: the solutions eluted in each gradient in step (2) were filtered through a 400-mesh nylon net, and the elution filtrates of each gradient were obtained; (4) concentration: the elution filtrates of each gradient in step (3) were concentrated under reduced pressure by using a rotary evaporator (65°C, 60 mbar) until there was no liquid dripping. The density of the concentrated solution was controlled to be 1.1920-1.208 g / cm 3< , and 4 components were respectively obtained, which were labeled as sample 1-1, sample 1-2, sample 1-3, and sample 1-4; and (5) each component in step (4) was formulated into an aerosol-forming material according to the above aerosol-forming material formula (the concentrated sample component accounted for 2 wt%, the solvent accounted for 98 wt%, and the solvent was a mixed solvent of propylene glycol and glycerol with a mass ratio of 6:4). According to the "Aroma Style Evaluation Form for Tobacco-flavored E-cigarettes" in the enterprise standard "Sensory Evaluation Standard for Tobacco-flavored E-cigarettes" (see Table 1), sensory evaluation was carried out on each component by 7 professional sensory evaluators and summarized. During the sensory evaluation, if the relevant aroma note was perceived, it was ticked in the corresponding box in the evaluation form of Table 1. The aroma note ticked by 4 or more evaluators was defined as the primary aroma note, and the aroma note ticked by 3 or fewer evaluators was defined as the secondary aroma note, and the sensory evaluation results were obtained (see Table 2). Table 1CategoryIndicatorSample 1-1Sample 1-2Sample 1-3Sample 1-4Tobacco aromaCharacteristic aroma of category AHay aromaBean aromaRoasted aromaCocoa aromaSweet aromaBurnt aromaWoody aromaSmoky aromaCharacteristic aroma of category BFruity aromaSpicy aromaHerbaceous aromaGreen aromaFloral aromaWine aromaMilk aromaComprehensive description:Sensory evaluatorDate:Note: a burnt-sweet aroma is a burnt aroma mingled with a sweet aroma. Table 2 Component numberSensory evaluationSample 1-1Roasted aroma and smoky aromaSample 1-2The primary aroma notes are a burnt-sweet aroma and a roasted aromaSample 1-3The primary aroma notes are a hay aroma, a floral aroma and a fruity aromaSample 1-4Hay aroma and green aroma (6) the aroma component analysis was performed on the component with an obvious burnt-sweet aroma note (sample 1-2). The specific analysis method was as follows: preparation of the sample to be tested: 500 µL of the component with an obvious burnt-sweet aroma note (sample 1-2) obtained in step (4) and 500 µL of the ethanol extract of Yun 87 were separately pipetted into centrifuge tubes. Then, 500 µL of a dichloromethane solution containing internal standards (the internal standards were 10.0 mg / mL of 2-methyl-3-heptanone and 2-octanol respectively) was added. Oscillation (3000 rpm) was performed for 10 min for sufficient extraction, followed by centrifugation (10000 rpm) for 5 min. An appropriate amount of the extraction solution was taken, passed through a 0.24-µm organic-phase filter membrane, and transferred to a chromatography vial for GC-MS / MS analysis. determination of aroma components: the determination of aroma components was performed on a GC-MS / MS (model: Agilent 5977B GC / MSD 8890GC System). The specific parameters were as follows: the chromatographic column was a DB-5MS ultra-inert column (60 m, 0.25 mm, 0.25 µm); split injection 10: 1; injection volume 1 µL; column oven temperature: kept at 40°C for 2 minutes, then increased to 150°C at a rate of 3°C / min and kept for 2 min, then increased to 300°C at a rate of 5°C / min and kept for 1 min, and finally increased to 320°C at a rate of 10°C / min and kept for 1 min; MSD temperature 280°C; solution delay 5.8 min; scanning range: 35-550; threshold: 150; scanning speed N = 2; and mass spectrometry adopted full-scan mode. The data were compared with those in the NIST20 library through retrieval. Each component was investigated and determined one by one. The representative substances of the burnt-sweet aroma note were analyzed both qualitatively and quantitatively to demonstrate the enrichment effect. Moreover, through data retrieval and manual verification, combined with literature review on the aroma note characteristics of aroma components, 4 common components (furfural, 3-methyl-1,2-cyclopentenedione, maltol, 2-cyclopentene-1,4-dione) were used as the representation of the burnt-sweet aroma note (see Table 3). The comparison of aroma components is shown in FIG. 1. Table 3 Component nameRetention time (Rt / min )Aroma note characterizationComponent content in the ethanol extract of Yun 87 (µg / mL) (µg / mL)Example 1 Component content in sample 1-2 (µg / mL)Comparative Example 1 Component content in sample 2-2 (µg / mL)Furfural52.26Toast-like aroma, woody aroma7.8425.060.672-cyclopentene-1,4-dione54.27Burnt-sweet aroma10.1936.320.463-methyl-1,2-cyclopentenedione54.56Caramel-like aroma6.1822.120.17Maltol58.01With a special flavor of burnt butterscotch12.8923.141.07 Example 2

[0025] This example provided a method for enriching a burnt-sweet aroma note in a Yunnan flue-cured tobacco extract, and the specific steps and operating parameters were as follows: (1) sample dilution: the Yunnan flue-cured tobacco extract (ethanol extract of Yun 87) was diluted with ethanol as the diluent according to a mass ratio of 1:1 to obtain a diluted solution; (2) medium-pressure preparation: the diluted solution obtained in step (1) was subjected to gradient elution using a medium-pressure preparative C18 column (Daiso RPS C18, 50 um, 2.0 kg of packing material, column size 460 × 100 mm). A 5% aqueous ethanol solution and a 38 wt% aqueous ethanol solution were separately used as the elution solutions. Under a pressure of 5 bar, gradient elution was performed at a flow rate of 20 mL / min, and the amount of each eluent was 4 BV. The solutions eluted in each gradient were collected; (3) filtration: the solutions eluted in each gradient in step (2) were filtered through a 400-mesh nylon net, and the elution filtrates of each gradient were obtained; (4) concentration: the elution filtrates of each gradient in step (3) were concentrated under reduced pressure by using a rotary evaporator (65°C, 60 mbar) until there was no liquid dripping. The density of the concentrated solution was controlled to be 1.1920-1.208 g / cm 3< , and the corresponding concentrated components eluted with the aqueous ethanol solutions were respectively obtained. Example 3

[0026] This example provided a method for enriching a burnt-sweet aroma note in a Yunnan flue-cured tobacco extract, and the specific steps and operating parameters were as follows: (1) sample dilution: the Yunnan flue-cured tobacco extract (ethanol extract of Yun 87) was diluted with water as the diluent according to a mass ratio of 1:5 to obtain a diluted solution; (2) medium-pressure preparation: the diluted solution obtained in step (1) was subjected to gradient elution using a medium-pressure preparative C18 column (Daiso RPS C18, 50 um, 2.0 kg of packing material, column size 460 × 100 mm). A 9 wt% aqueous ethanol solution and a 40 wt% aqueous ethanol solution were separately used as the elution solutions. Under a pressure of 20 bar, gradient elution was performed at a flow rate of 80 mL / min, and the amount of each eluent was 3 BV. The solutions eluted in each gradient were collected; (3) filtration: the solutions eluted in each gradient in step (2) were filtered through a 400-mesh nylon net, and the elution filtrates of each gradient were obtained; (4) concentration: the elution filtrates of each gradient in step (3) were concentrated under reduced pressure by using a rotary evaporator (45°C, 120 mbar) until there was no liquid dripping. The density of the concentrated solution was controlled to be 1.1920-1.208 g / cm 3< , and the corresponding concentrated components eluted with the aqueous ethanol solutions were respectively obtained. Comparative Example 1

[0027] This comparative example provided a method for enriching a burnt-sweet aroma note in a Yunnan flue-cured tobacco extract, and the specific steps and operating parameters were as follows: (1) sample dilution: the Yunnan flue-cured tobacco extract (ethanol extract of Yun 87) was diluted with propylene glycol as the diluent according to a mass ratio of 1:3 to obtain a diluted solution; (2) medium-pressure preparation: the diluted solution obtained in step (1) was subjected to gradient elution using a medium-pressure preparative C8 column (Daiso RPS C8, 50 um, 2.0 kg of packing material, column size 460 × 100 mm). Water, a 40% aqueous ethanol solution, an 80% aqueous ethanol solution, and a 95% aqueous ethanol solution were separately used as the elution solutions. Under a pressure of 10 bar, gradient elution was performed at a flow rate of 50 mL / min, and the amount of each eluent was 5 BV. The solutions eluted in each gradient were collected; (3) filtration: the solutions eluted in each gradient of the aqueous ethanol solution in step (2) were filtered through a 400-mesh nylon net, and the elution filtrates of each gradient were obtained; (4) concentration: the elution filtrates of each gradient in step (3) were concentrated under reduced pressure by using a rotary evaporator (65°C, 60 mbar) until there was no liquid dripping. The density of the concentrated solution was controlled to be 1.1920-1.208 g / cm 3< , and 4 components were respectively obtained, which were labeled as sample 2-1, sample 2-2, sample 2-3, and sample 2-4; and (5) each component in step (4) was formulated into an aerosol-forming material according to the above aerosol-forming material (the concentrated sample component accounted for 2 wt%, the solvent accounted for 98 wt%, and the solvent was a mixed solvent of propylene glycol and glycerol with a mass ratio of 6:4). According to the "Aroma Style Evaluation Form for Tobacco-flavored E-cigarettes" in the enterprise standard "Sensory Evaluation Standard for Tobacco-flavored E-cigarettes" (see Table 1), sensory evaluation was carried out on each component by 7 professional sensory evaluators and summarized. During the sensory evaluation, if the relevant aroma note was perceived, it was ticked in the corresponding box in the evaluation form of Table 1. The aroma note ticked by 4 or more evaluators was defined as the primary aroma note, and the aroma note ticked by 3 or fewer evaluators was defined as the secondary aroma note, and the sensory evaluation results were obtained (see Table 4). In addition, the components with obvious burnt-sweet aroma notes were subjected to an analysis of their aroma components (the specific analysis method was the same as that in Example 1). Moreover, through data retrieval and manual verification, combined with literature review on the aroma note characteristics of aroma components, 4 common components (furfural, 3-methyl-1,2-cyclopentenedione, maltol, 2-cyclopentene-1,4-dione) were used as the representation of the burnt-sweet aroma note. The comparison of aroma components is shown in FIG. 1. Table 4Component numberSensory evaluationSample 2-1Roasted aroma and smoky aromaSample 2-2The primary aroma note is a smoky aroma, with a burnt-sweet aroma.Sample 2-3The primary aroma note is a hay aroma, with a burnt-sweet aroma at the base.Sample 2-4Hay aroma, green aroma, floral aroma, and fruity aroma

[0028] From the comparison of the experimental results of the ethanol extract of Yun 87, the examples, and the comparative examples, the enrichment method provided in the present disclosure could enrich the small-amount substances of the burnt-sweet aroma note in the ethanol extract of Yun 87 and remove impurities. When applied to the aerosol-forming material, it made the burnt-sweet aroma note prominent and the tobacco aroma harmonious and natural. However, the samples provided by the comparative examples contained more impurities and could not effectively enrich the target components.Comparative Example 2

[0029] This comparative example provided a method for enriching a burnt-sweet aroma note in a Yunnan flue-cured tobacco extract. Compared with Example 1, the only difference was that no pressure was applied in the elution process, and the elution was performed at normal pressure.

[0030] This led to a very slow separation efficiency, so that the key target components diffused in different eluents and could not be effectively enriched.Comparative Example 3

[0031] This comparative example provided a method for enriching a burnt-sweet aroma note in a Yunnan flue-cured tobacco extract. Compared with Example 1, the only difference was that a macroporous resin column (D101, 0.3 mm) was used instead of the C18 column.

[0032] The particle size of the macroporous resin was between 0.3-1.25 mm, and the material was a polymer. The separation degree was low, and the target effective components could not be concentrated and enriched. Each sample contained components of the burnt aroma note.Comparative Example 4

[0033] This comparative example provided a method for enriching a burnt-sweet aroma note in a Yunnan flue-cured tobacco extract. Compared with Example 1, the only difference was that a 40 wt% aqueous methanol solution was used instead of the 40 wt% aqueous ethanol solution in step (2).

[0034] Since the polarity of methanol is greater than that of ethanol, if 40% methanol is used to replace ethanol, some impurities with relatively high polarity will be introduced during the enrichment of the effective components. Moreover, methanol is a toxic solvent and is not suitable as a solvent for electronic atomization devices as it is harmful to the body.

[0035] Obviously, the above examples were merely illustrations for clear description and not limitations on the embodiments. For those of ordinary skill in the art, other different forms of changes or variations could be made based on the above description. All embodiments need not and cannot be exhaustive herein. However, the obvious changes or variations derived therefrom still fall within the scope of protection of the present disclosure.

Claims

1. A method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco, comprising steps of: S1: diluting a Yunnan flue-cured tobacco extract with a diluent to obtain a diluted solution; S2: subjecting the obtained diluted solution to an elution treatment using a C18 column under a pressure of 5-20 bar, wherein the elution treatment comprises: first performing a primary elution with a first eluent, then performing a secondary elution with a second eluent, and collecting a secondary elution solution, wherein the first eluent is water or an aqueous ethanol solution with a mass concentration of less than 10%, and the second eluent is an aqueous ethanol solution with a mass concentration of 38-42%; and S3: concentrating the collected secondary elution solution to obtain a sample with the burnt-sweet aroma note.

2. The method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco of claim 1, wherein in step S2, the flow rate of the elution treatment is 20 mL / min-80 mL / min.

3. The method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco of claim 1, wherein in step S2, the amount of the first eluent is 3 BV-5 BV; and / or the amount of the second eluent is 3 BV-5 BV.

4. The method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco of any one of claims 1-3, wherein in step S1, the mass ratio of the Yunnan flue-cured tobacco extract to a solvent is 1:1-1:5.

5. The method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco of any one of claims 1-3, wherein in step S1, the diluent comprises at least one of water, ethanol, propylene glycol, and glycerol.

6. The method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco of any one of claims 1-3, wherein in step S3, concentration under reduced pressure is adopted; and / or the concentration is performed until the density of a concentrated solution is 1.1920-1.208 g / cm3.

7. The method for enriching a burnt-sweet aroma note in Yunnan flue-cured tobacco of claim 6, wherein in step S3, the temperature for the concentration under reduced pressure is 45-65°C, and the pressure for the concentration under reduced pressure is 60-120 mbar.

8. A sample of a burnt-sweet aroma note of Yunnan flue-cured tobacco enriched by the method of any one of claims 1-7, comprising 20-30 µg / mL of furfural, 20-30 µg / mL of 3-methyl-1,2-cyclopentenedione, 20-25 µg / mL of maltol, and 35-40 µg / mL of 2-cyclopentene-1,4-dione.

9. An aerosol-forming material, comprising the sample of a burnt-sweet aroma note of Yunnan flue-cured tobacco of claim 8.

10. The aerosol-forming material of claim 9, wherein the aerosol-forming material is atomization liquid, comprising 0.5-2 wt% of the sample of the burnt-sweet aroma note of Yunnan flue-cured tobacco and 98-99.5 wt% of a solvent; optionally, the solvent is a mixed solvent of propylene glycol and glycerol; and further optionally, the mass ratio of the propylene glycol to the glycerol is 6:4-1: 1.

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